Stack of electrical components and method of producing the same

ABSTRACT

A stack of electrical components has a first electrical component having a first surface, a second surface that is opposite to the first surface and a side surface that is located between the first surface and the second surface; a second electrical component having a third surface on which the first electrical component is mounted, the third surface facing the second surface and forming a corner portion between the third surface and the side surface; an adhesive layer that bonds the first electrical component to the second electrical component, the adhesive layer has a first portion that is located between the second and third surface and a second portion that is made of a same material as the first portion and that fills the corner portion; and a conductive layer that extends on a side of the side surface, curves along the second portion and extends to the third surface.

The present application is a continuation application of U.S. patentapplication Ser. No. 16/556,809 filed on Aug. 30, 2019, and claimsbenefit of priority from, Japanese Patent Application No. 2018-193174filed on Oct. 12, 2018, the disclosures of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a stack of electrical components and amethod of producing the same, particularly to a stack of electricalcomponents in which an ASIC (application-specific integrated circuit)and a magnetic sensor are stacked.

Description of the Related Art

A technique is known in which a package is formed by mounting anelectrical component, such as an integrated circuit, a semiconductorelement, a MEMS and a magnetic sensor, on another electrical component.U.S. Pat. No. 9,466,580 discloses a semiconductor package in which asemiconductor die (hereinafter, referred to as a first electricalcomponent) is mounted on another semiconductor die (hereinafter,referred to as a second electrical component). A pad that is formed onthe upper surface of the first electrical component is connected to apad that is formed on the upper surface of the second electricalcomponent (the surface on which the first electrical component ismounted) via a conductive layer (a redistribution layer). An insulatinglayer (a passivation layer) is provided on the side surface of the firstelectrical component, and the conductive layer is formed along theinsulating layer. The side surface of the insulating layer is formed inan inclined shape, and the conductive layer is provided along the sidesurface of the insulating layer thus formed.

SUMMARY OF THE INVENTION

Generally, in order to downsize a stack of electrical components inwhich a first electrical component is mounted on a second electricalcomponent, it is desirable to downsize the second electrical component.In order to downsize the second electrical component, there may be aneed to arrange the pad of the second electrical component close to thefirst electrical component. If the conductive layer can be arrangedalong the side surface of the first electrical component, then therequired distance between the pad of the second electrical component andthe first electrical component is minimized, and the limitation on thedownsizing of the second electrical component can be mitigated. However,because the conductive layer has to be bent substantially at rightangles at the corner portion that is formed by the upper surface of thesecond electrical component and the side surface of the first electricalcomponent, the electrical reliability of the conductive layer maydeteriorate.

The present invention aims at providing a stack of electrical componentsin which a conductive layer can be arranged along the side surface of afirst electrical component while securing the electrical reliability ofthe conductive layer, as well as a method of producing the stack ofelectrical components.

A stack of electrical components of the present invention comprises: afirst electrical component having a first surface, a second surface thatis opposite to the first surface and a side surface that is locatedbetween the first surface and the second surface; a second electricalcomponent having a third surface on which the first electrical componentis mounted, the third surface facing the second surface and forming acorner portion between the third surface and the side surface; anadhesive layer that bonds the first electrical component to the secondelectrical component, the adhesive layer has a first portion that islocated between the second surface and the third surface and a secondportion that is made of a same material as the first portion and thatfills the corner portion; and a conductive layer that extends on a sideof the side surface, curves along the second portion and extends to thethird surface.

A method of producing a stack of electrical components of the presentinvention comprises: mounting a first electrical component on a secondelectrical component, and bonding the first electrical component to thesecond electrical component by an adhesive layer, wherein the firstelectrical component has a first surface, a second surface that isopposite to the first surface and side surface that is located betweenthe first surface and the second surface, the second surface of thefirst electrical component faces a third surface of the secondelectrical component, and the third surface forms a corner portionbetween the third surface and the side surface, and providing aconductive layer that extends on a side of the side surface and furtherextends to the third surface. The adhesive layer is provided such thatthe adhesive layer has a first portion that is located between thesecond surface and the third surface, as well as a curved second portionthat fills the corner portion, and the conductive layer is provided tocurve along the second portion.

According to the present invention, a part of the adhesive layer thatbonds the first electrical component to the second electrical componentis a curved second portion that fills the corner portion that is formedbetween the third surface and the side surface, and the conductive layercurves along the second portion. Accordingly, the conductive layer doesnot need to make a sharp turn at the corner portion. Therefore, thepresent invention can provide a stack of electrical components in whicha conductive layer can be arranged along a side surface of a firstelectrical component while securing the electrical reliability of theconductive layer, as well as a method of producing the stack ofelectrical components.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description withreference to the accompanying drawings which illustrate examples of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a top view and a cross-sectional view illustrating astack of electrical components according to a first embodiment,respectively;

FIG. 2 is a cross-sectional view illustrating the stack in FIGS. 1A and1B in more detail;

FIGS. 3A to 3C are partial cross-sectional views illustrating the stackin FIGS. 1A and 1B in more detail;

FIGS. 4A to 4C are perspective views illustrating various modificationsof the holding means;

FIGS. 5A to 5C are process diagrams schematically illustrating a methodof producing the first electrical component;

FIGS. 6A to 6D are process diagrams schematically illustrating a methodof producing the stack according to the first embodiment;

FIGS. 7A and 7B are diagrams illustrating the advantages of the stackaccording to the first embodiment;

FIG. 8 is a top view illustrating the stack of electrical componentsaccording to a second embodiment;

FIGS. 9A and 9B are cross-sectional views illustrating the stack in FIG.8;

FIGS. 10A and 10B are partial cross-sectional views illustrating thestack in FIG. 8 in more detail;

FIGS. 11A to 11G are process diagrams schematically illustrating amethod of producing the stack according to the second embodiment;

FIG. 12 is a cross-sectional view of a stack according to anothermodification; and

FIG. 13 is a cross-sectional view of a stack according to yet anothermodification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings. The present invention relates to a stack (apackage) of electrical components in which a first electrical componentis mounted on a second electrical component. In the followingembodiments, the first electrical component is a magnetic sensor, andthe second electrical component is an ASIC (application-specificintegrated circuit) that is connected to the magnetic sensor, but thepresent invention is not limited to this.

First Embodiment

FIG. 1A is a top view illustrating a stack of electrical components(hereinafter, referred to as stack 1), and FIG. 1B is a cross-sectionalview illustrating stack 1 taken along line A-A in FIG. 1A. FIG. 2 is across-sectional view illustrating stack 1 in more detail, and FIGS. 3Ato 3C are partial cross-sectional views illustrating portion A, portionB, and portion C in FIG. 2 in more detail, respectively.

First electrical component 2 has an approximately rectangularparallelepiped shape. First electrical component 2 has first surface 21,second surface 22 that is a surface opposite to first surface 21 andfirst side surfaces 23 that are located between first surface 21 andsecond surface 22. First electrical component 2 has first electricalconnections 24 on first surface 21. First electrical component 2 hasfirst substrate 25 made of silicon, as well as first passivation layer26 that is provided on first substrate 25. A sensor element, such as aTMR element (not illustrated), is formed in first substrate 25. Firstpassivation layer 26 is an insulating layer that protects firstsubstrate 25, and first surface 21 a is formed by the surface of firstpassivation layer 26. In each first electrical connection 24, first pad27 is formed on the surface of first substrate 25, and first passivationlayer 26 includes first opening 28 that exposes first pad 27.

Second electrical component 3 has an approximately rectangularparallelepiped shape. Second electrical component 3 has third surface31, fourth surface 32 that is a surface opposite to third surface 31 andsecond side surfaces 33 that are located between third surface 31 andfourth surface 32. Third surface 31 of second electrical component 3faces second surface 22 of first electrical component 2. A part of thirdsurface 31 works as the mounting surface on which first electricalcomponent 2 is mounted, and first electrical component 2 is bonded tosecond electrical component 3 via adhesive layer 4 on the mountingsurface. Second electrical connections 34 are provided on third surface31 at positions different from the mounting surface. Second electricalcomponent 3 has second substrate 35 made of silicon, as well as secondpassivation layer 36 that is provided on second substrate 35. Anelement, such as an IC (not illustrated), is formed in second substrate35. Second passivation layer 36 is an insulating layer that protectssecond substrate 35, and third surface 31 is formed by the surface ofsecond passivation layer 36. In each second electrical connection 34,second pad 37 is formed on the surface of second substrate 35, andsecond passivation layer 36 has second opening 38 that exposes secondpad 37. Second electrical component 3 is larger than first electricalcomponent 2, and third surface 31 of second electrical component 3 islarger than second surface 22 of first electrical component 2.Specifically, second surface 22 of first electrical component 2 islocated inside the circumference of third surface 31 of secondelectrical component 3. Accordingly, corner portion K havingapproximately right angles is formed between third surface 31 of secondelectrical component 3 and first side surface 23 of first electricalcomponent 2. As described later, second electrical connections 34 areconnected to first electrical connections 24 via conductive layers 5.External connecting pads 39 for connection to the outside are providednear the circumference of third surface 31 of second electricalcomponent 3. As illustrated in FIG. 1B, stack 1 is connected to anotherdevice via wire W that is connected to external connecting pad 39.

Adhesive layer 4 is made of a silicone resin. Due to the highheat-resisting capability, adhesive layer 4 can withstand heat treatmentat a high temperature in the wafer process. Adhesive layer 4 has firstportion 41 that is located between second surface 22 and third surface31, as well as curved-shaped second portion 42 that fills corner portionK. First portion 41 mainly has the function of bonding first electricalcomponent 2 to second electrical component 3. A part of second portion42 is formed of a liquid resin that is provided outside first electricalcomponent 2 in advance, and the remaining portion is formed of a resinthat is forced out of the space between second surface 22 and thirdsurface 31 when first electrical component 2 is bonded to secondelectrical component 3. Accordingly, second portion 42 is formed on theside of first portion 41, as well as in the region of first side surface23 that is close to third surface 31 (hereinafter, referred to as lowerportion 23 b). Since the resin goes up along first side surface 23 dueto surface tension thereof, a part of adhesive layer 4 (not illustrated)is also formed in the region of first side surface 23 between secondportion 42 and first surface 21 (hereinafter, referred to as upperportion 23 a), although the amount of the resin thus formed is limited.In the present invention, it is not essential whether a part of adhesivelayer 4 is formed in upper portion 23 a, and the amount of adhesivelayer 4 that is formed in upper portion 23 a is not essential. Theboundary between upper portion 23 a and lower portion 23 b is locatedcloser to third surface 31 than the midpoint of first side surface 23 inthe height direction, but the boundary may also be located closer tofirst surface 21 than the midpoint.

Suppose that thickness t of second portion 42 is defined as a thicknessthat is measured along a normal line to first side surface 23 in theregion of first side surface 23, and is defined as a thickness that ismeasured along a normal line to an extension of first side surface 23 inthe region between first electrical component 2 and second electricalcomponent 3. Thickness t of second portion 42 thus defined monotonicallyincreases toward third surface 31 of second electrical component 3. Inaddition, the rate of increase of thickness t monotonically increasestoward third surface 31 in at least the area that is closer to thirdsurface 31 than the center of first side surface 23 in the thicknessdirection (the middle position equidistant both from first surface 21and third surface 31). In other words, second portion 42 has a curvedshape that is concave toward corner portion K near corner portion K, andsubstantially has a cross-section of a right triangle having a curvedhypotenus protruding toward corner portion K.

Holding means 6 for holding adhesive layer 4 is formed between thirdsurface 31 and adhesive layer 4. To be more exact, holding means 6 holdsa liquid adhesive (resin) that is cured to be converted into adhesivelayer 4. In the present embodiment, wettability control layer 61 havinglarger wettability than third surface 31 is formed as holding means 6.Wettability control layer 61 is formed between adhesive layer 4 andthird surface 31. The wettability refers to the tendency of a liquid tobe wettable on a solid surface. The smaller the contact angle (an angleformed between a surface of stationary liquid and a solid surface wherethe free surface of the liquid meets the solid wall) is, the higher isthe wettability. Wettability control layer 61 is a metal layer (a metalland) that is formed on third surface 31 and that forms a step betweenthe layer and third surface 31. Specifically, wettability control layer61 forms a portion that protrudes toward first electrical component 2from the surrounding third surface 31. Wettability control layer 61 is,for example, made of metal, such as Cu, but may be formed of anymaterial that can hold a liquid resin that is to be converted intoadhesive layer 4. In the present embodiment, wettability control layer61 is formed by plating, and second seed layer 65 for the plating ofwettability control layer 61 is provided between second passivationlayer 36 and wettability control layer 61. Second seed layer 65 is madeof Cu and may be formed by sputtering. When wettability control layer 61is formed by sputtering, CVD, or the like, second seed layer 65 is notnecessary. The circumference of wettability control layer 61 is formedoutside the circumference of first electrical component 2 along theentire circumference thereof, as viewed in the direction perpendicularto third surface 31.

A part of second portion 42 is formed of a resin that is forced out ofthe space between second surface 22 and third surface 31. Therefore, theresin preferably has a viscosity as low as possible in order to formsecond portion 42 with high accuracy and with high reproducibility ofshape. However, if a resin having a low viscosity is used, then theresin may spread extensively on third surface 31. Because wettabilitycontrol layer 61 has a larger wettability than third surface 31, thearea where the applied resin spreads is limited within the circumferenceof wettability control layer 61. A step is formed between wettabilitycontrol layer 61 and third surface 31 such that wettability controllayer 61 is on the upper side and third surface 31 is on the lower side.Accordingly, the area where the applied resin spreads is also limited bythe surface tension that is generated along the circumference ofwettability control layer 61.

Holding means 6 is not limited to the arrangement described above, andmay be modified in various manners. For example, as illustrated in FIG.4A, holding unit 6 may be holding surface 62 for an adhesive layer thatis formed on third surface 31 and that has a larger wettability than theother portions of third surface 31. Holding surface 62 having a largerwettability than third surface 31 may be formed by rough surfacefinishing of third surface 31. In this modification, a step betweenholding surface 62 and third surface 31 is not necessary. As illustratedin FIG. 4B, holding means 6 may be recess 63 that is recessed from thirdsurface 31 in a direction away from first electrical component 2. Inthis modification, recess 63 holds the adhesive, and the wettability ofthe bottom surface of recess 63 is not limited. As illustrated in FIG.4C, holding means 6 may be frame member 64 that is provided on thirdsurface 31. In this modification, frame member 64 holds the adhesive,and the wettability of the bottom surface inside frame member 64 is notlimited. Furthermore, although not illustrated, wettability controllayer 61 may be embedded in second passivation layer 36 such thatwettability control layer 61 is flush with third surface 31.

As illustrated in FIGS. 1A, 1B and 2, first electrical connections 24(first pads 27) are connected to second electrical connections 34(second pads 37) via conductive layers 5 (redistribution layers).Conductive layers 5 are strip-shaped metal layers that connect firstelectrical connections 24 to second electrical connections 34. In thepresent embodiment, four conductive layers 5 are provided, but thenumber of conductive layers 5 is not limited to this. Each conductivelayer 5 extends from first electrical connection 24 to second electricalconnection 34 along first surface 21, then along second portion 42 ofadhesive layer 4 (that is, extends on the side of first side surface 23toward third surface 31), then along third surface 31 of secondelectrical component 3. In the present embodiment, each conductive layer5 terminates at second electrical connection 34. In upper portion 23 aof first side surface 23, conductive layer 5 substantially extends alongfirst side surface 23. Conductive layer 5 is made of Cu, but may be madeof other conductive materials, such as Au, Ag and Al. In the presentembodiment, conductive layer 5 is formed by plating, but may be formedby other methods, such as sputtering and CVD. Conductive layer 5 curvesalong second portion 42, which is formed in a curved shape near cornerportion K, and therefore conductive layer 5 does not sharply change thedirection. This makes it easy to secure the electrical reliability ofconductive layer 5.

First insulating layer 7 is provided both between conductive layer 5 andfirst side surface 23 and between conductive layer 5 and first surface21 in order to secure electrical insulation between conductive layer 5and first substrate 25. First insulating layer 7 is also providedbetween conductive layer 5 and third surface 31. First insulating layer7 is made of SiO₂, SiN, AlO, or the like, and may be formed by CVD.First seed layer 51 is provided on the outer surface of first insulatinglayer 7 for the plating of conductive layer 5. First seed layer 51 ismade of Cu and may be formed by sputtering. When conductive layer 5 isformed by sputtering, CVD, or the like, first seed layer 51 is notnecessary. The outer surface of conductive layer 5 is covered with andprotected by third passivation layer 8. As illustrated in FIG. 3A, firstopening 28 to expose first pad 27 is provided both in first passivationlayer 26 and in first insulating layer 7 around first electricalconnection 24, and first seed layer 51 is also formed on the side wallof first opening 28, as well as on first pad 27. Thus, the electricalconnection between conductive layer 5 and first pad 27 can beestablished. Similarly, as illustrated in FIG. 3C, second opening 38 toexpose second pad 37 is provided both in second passivation layer 36 andin first insulating layer 7 around second electrical connection 34, andfirst seed layer 51 is also formed on the side wall of second opening38, as well as on second pad 37. Thus, the electrical connection betweenconductive layer 5 and second pad 37 can be established.

Next, a method of producing above-described stack 1 will be described.In this producing method, first electrical components 2 and secondelectrical components 3 are formed in different wafer processes (formedon different wafers), and first electrical component 2 that is separatedis mounted on second electrical component 3 that is provided on thewafer. First, as illustrated in FIG. 5A, wafer W on which a plurality offirst electrical components 2 are formed is attached to adhesive sheetS1 for fixation. Adhesive sheet S1 is attached to the surface of thewafer opposite to the surface (second surface 22) on which firstelectrical connection 24 is formed. First electrical components 2 arecut halfway in the thickness of wafer W (half cutting) from the backsurface of first electrical components 2, as viewed from adhesive sheetS1. Next, as illustrated in FIG. 5B, adhesive sheet S1 is removed, waferW is turned upside down and is attached to another adhesive sheet S2 forfixation. That is, first electrical components 2 are attached to anotheradhesive sheet S2 such that the surfaces of first electrical components2 that have been cut contact adhesive sheet S2. In this state, thesurfaces of first electrical components 2 that have not been cut areground in order to thin first electrical components 2 until no uncutportion remains. Thus, first electrical components 2 are separated onadhesive sheet S2. By using such a cutting method that involves the halfcutting, chipping can be prevented during the cutting process even whenfirst electrical components 2 are thinned. Next, as illustrated in FIG.5C, another adhesive sheet S3 is attached, wafer W is turned upsidedown, and adhesive sheet S2 is removed. Thus, first electricalcomponents 2 that are separated can be picked up and can be easilymounted on respective second electrical components 3. When a device isused that can directly mount first electrical component 2 on secondelectrical component 3 in the state illustrated in FIG. 5B, the processillustrated in FIG. 5C can be omitted.

Next, as illustrated FIG. 6A, adhesive 43 is applied to third surface 31of each second electrical component 3 on the wafer. Adhesive 43 is aliquid resin. Specifically, second seed layer 65 is formed on secondpassivation layer 36 of second electrical component 3, and wettabilitycontrol layer 61 is formed on second seed layer 65 by plating (notillustrated in FIG. 6A, see FIGS. 2 and 3B). Next, liquid adhesive 43 isapplied to wettability control layer 61. Adhesive 43 spreads to coverthe upper surface of wettability control layer 61. Adhesive 43 does notcover the entire upper surface of wettability control layer 61, butpreferably spreads on the upper surface of wettability control layer 61over the area that allows the entire bottom surface of first electricalcomponent 2 to contact adhesive 43. In other words, the area of secondsurface 22 of first electrical component 2 is smaller than the areawhere adhesive 43 spreads. This enables second portion 42 to be formedalong the entire circumference of second surface 22 of first electricalcomponent 2. Adhesive 43 may cover the entire upper surface ofwettability control layer 61. Because the area of wettability controllayer 61 is larger than the area of second surface 22 of firstelectrical component 2, second portion 42 is formed along the entirecircumference of second surface 22 of first electrical component 2. Itshould be noted that a plurality of second electrical components 3 isformed on the wafer, although only one second electrical component 3 isillustrated in FIGS. 6A to 6D. Next, as illustrated in FIG. 6B, firstelectrical component 2 is mounted on wettability control layer 61 thatis covered with adhesive 43. Second surface 22 of first electricalcomponent 2 faces third surface 31 of second electrical component 3, andcorner portion K is formed between third surface 31 of second electricalcomponent 3 and first side surface 23 of first electrical component 2. Apart of adhesive 43 is forced out of the space between second surface 22and third surface 31 due to the weight of first electrical component 2or by controlling pressing force, and goes up along first side surface23 (see FIG. 2). Thus, second portion 42 is formed. The reproducibilityof the shape of second portion 42 can be secured by adjusting the amountof adhesive 43, the moving velocity of first electrical component 2, thepressing force and so on. When a thermosetting resin is used as adhesive43, first electrical component 2 is bonded to second electricalcomponent 3 by heating the resin in order to form second portion 42.Adhesive 43 is then cured to be converted into adhesive layer 4.

Next, as illustrated in FIG. 6C, conductive layer 5 that connects firstelectrical connection 24 on first surface 21 to second electricalconnection 34 on third surface 31 is formed. Specifically, firstinsulating layer 7 (see FIGS. 2, and 3A to 3C) is formed first on firstsurface 21 and first side surface 23 of first electrical component 2, aswell as on third surface 31 of second electrical component 3. Firstinsulating layer 7 may be formed, for example, by CVD. In this case, thesurface of adhesive layer 4 is also covered with first insulating layer7. Next, the portions of first insulating layer 7 immediately abovefirst and second pads 27 and 37 are removed in order to expose first andsecond pads 27 and 37. Then, conductive layer 5 is formed according tothe following processes. First seed layer 51 is formed first on firstinsulating layer 7, as well as on first and second pads 27 and 37 thathave been exposed. Next, a resist is formed on first seed layer 51, andthe portion of the resist on which conductive layer 5 is to be formed isremoved by patterning in order to expose first seed layer 51. Then, thewafer is immersed in a plating bath in order to plate the portion offirst seed layer 51 that has been exposed. Since the plating is formedin a curved shape along second portion 42, conductive layer 5 cangradually change the direction from first side surface 23 of firstelectrical component 2 toward third surface 31 of second electricalcomponent 3, as described above. Then, the resist is removed, and theportion of first seed layer 51 that has not been plated is removed bymeans of milling, or the like. Subsequently, third passivation layer 8is formed on conductive layer 5. Third passivation layer 8 may beformed, for example, by CVD. As illustrated in FIG. 6D, externalconnecting pad 39 is then formed on third surface 31 of secondelectrical component 3. Thereafter, the wafer, on which secondelectrical components 3 are formed, is cut in order to separate stacks1, although not illustrated.

Next, the advantages of the present embodiment will be described. Cornerportion K that is formed by first electrical component 2 and secondelectrical component 3 is a portion where it is difficult to form ametal layer and to secure the electrical reliability of conductive layer5, regardless of how conductive layer 5 is formed (that is, regardlessof whether conductive layer 5 is formed by plating or whether formed bya method other than plating, such as sputtering). In the presentembodiment, second portion 42 of adhesive layer 4 is formed outsidefirst electrical component 2. Since second portion 42 is formed in acurved shape, it is possible to gradually change the direction ofconductive layer 5 near corner portion K by forming conductive layer 5along second portion 42. Accordingly, in the present embodiment, theelectrical reliability of conductive layer 5 can be easily secured.

Indeed, a member other than an adhesive can be used in order to form acurved portion in corner portion K, if possible. However, using such amember may complicate the manufacturing process and affect the cost. Inthe present embodiment, a liquid resin that is used to bond firstelectrical component 2 to second electrical component 3 is used toprovide the curved portion in corner portion K, and no additional memberis required. In addition, the deformation of the resin occursconcurrently when first electrical component 2 is mounted on secondelectrical component 3, and no special step for deforming the resin isrequired. In other words, adhesive layer 4 (adhesive 43) of the presentembodiment is not only used to bond first electrical component 2 tosecond electrical component 3, but is also used as a supporting layerfor conductive layer 5 by forcing adhesive layer 4 (adhesive 43) out offirst electrical component 2.

Furthermore, since conductive layer 5 can be substantially formed alongfirst side surface 23 of first electrical component 2, second electricalconnection 34 of second electrical component 3 can be arranged nearfirst electrical component 2. Thus, the limitation on the position ofsecond electrical connection 34 is mitigated, and second electricalcomponent 3, as well as stack 1 (package), can be downsized. Thedownsizing of second electrical component 3 leads to an increase in thenumber of second electrical components 3 obtained per wafer.

First insulating layer 7 is a thin film that is formed on first surface21 and first side surface 23 of first electrical component 2, as well ason third surface 31 of second electrical component 3. This leads to afurther advantage in the producing process. FIGS. 7A and 7B arecross-sectional views schematically illustrating the stack that isdisclosed in U.S. Pat. No. 9,466,580. As illustrated in FIG. 7A,inclined insulating layer 101 is formed on the side surface of firstelectrical component 2, and conductive layer 5 is formed along theinclined side surface. Since the thickness of insulating layer 101 thatis formed on third surface 31 is substantially the same as the height offirst electrical component 2, insulating layer 101 having substantiallythe same height as the height of first electrical component 2 is formedon first surface 21 of first electrical component 2, as illustrated inFIG. 7B. Accordingly, the portion of insulating layer 101 above thedashed line needs to be removed in advance in order to form conductivelayer 5 on first surface 21. In contrast, such a large step is notgenerated in first insulating layer 7 in the present embodiment. Theprocess of making first insulating layer 7 flat is not necessary, andthe process can be simplified.

Furthermore, first seed layer 51 to form conductive film 5 is alsoformed in portions other than the portion where conductive film 5 isformed. Thus, first seed layer 51 in the former needs to be removedafter the process of plating conductive film 5 is completed (after theresist is removed). It is very difficult to remove first seed layer 51when corner portion K forms right angles, but in the present embodiment,the boundary between first electrical component 2 and second electricalcomponent 3 is formed in a curved shape by adhesive layer 4, and firstseed layer 51 can be easily removed.

Second Embodiment

Stack 101 according to the second embodiment will be described withreference to FIGS. 8 to 11G. Hereinafter, differences from the firstembodiment will be mainly described. The configuration and effects thatare not particularly mentioned are the same as those of the firstembodiment. FIG. 8 is a top view illustrating stack 101 according to thesecond embodiment, and FIGS. 9A and 9B are cross-sectional views ofstack 101 taken along line A-A and line B-B of FIG. 8, respectively.FIGS. 10A and 10B are partial cross-sectional views illustrating portionD and portion E in FIG. 9A in more detail, respectively. It should benoted that portion A and portion B in FIG. 9A are the same as in thefirst embodiment. Refer to FIG. 3A to 3C and the above-mentioneddescription.

In the present embodiment, second portion 42 of adhesive layer 4 andconductive layer 5 are covered with molding material 9 that is made ofan epoxy resin. Conductive pillar 10 is connected to conductive layer 5.Conductive pillar 10 bypasses second electrical component 3 in order todirectly takes out the output of first electrical component 2. Whenpillar 10 is arranged immediately above first electrical component 2,stress that is generated when pillar 10 is connected to an externalconnecting portion (a solder ball, a wire, or the like) may be directlyapplied to first electrical component 2 through pillar 10. When firstelectrical component 2 is a magnetic sensor or a semiconductor element,the output may vary due to the influence of the stress. This problem canbe prevented by arranging pillar 10 outward of first electricalcomponent 2. Pillar 10 is made of the same material (Cu) as conductivelayer 5. The configurations of first electrical component 2, conductivelayer 5 and adhesive layer 4 are the same as in the first embodiment. Onthe other hand, as illustrated in FIG. 9A and 10B, second electricalcomponent 34 is not provided. In the connecting portion between pillar10 and conductive layer 5, second passivation layer 36 is provided onsecond substrate 35, and first insulating layer 7, fist seed layer 51and conductive layer 5 are provided on second passivation layer 36 inthis order. As illustrated in FIGS. 9A and 10A, conductive terminal 12for external connection is provided on the top end of pillar 10. Pillar10 is covered with third passivation layer 8 along the circumferencethereof.

As illustrated in FIG. 9B, third insulating layer 11 is provided betweensecond portion 42 of adhesive layer 4 and molding material 9. Due to thepoor adhesivity between the epoxy resin, which is the material ofmolding material 9, and the silicone resin, which is the material ofadhesive layer 4, the epoxy resin easily peels off from the siliconeresin. Third insulating layer 11 prevents adhesive layer 4 from directlycontacting molding material 9, thereby reducing the possibility ofmolding material 9 peeling off from adhesive layer 4.

An epoxy resin is used as molding material 9 in the present embodiment,but the epoxy resin may also be used as a coating film for secondportion 42 of adhesive layer 4. In this case also, third insulatinglayer 11 is preferably provided between the coating film made of theepoxy resin and second portion 42 of adhesive layer 4. Furthermore,third insulating layer 11 directly covers second portion 42 of adhesivelayer 4 in the present embodiment, but may indirectly cover secondportion 42 via another layer.

Next, a method of producing above-described stack 101 of electricalcomponents will be described. In this producing method also, firstelectrical components 2 and second electrical components 3 are formed indifferent wafer processes (formed on different wafers), and firstelectrical component 2 that is separated is mounted on second electricalcomponent 3 that is provided on the wafer. First electrical component 2is produced in the same manner as in the first embodiment. Refer to FIG.5A to 5C and the above-mentioned description.

Next, as illustrated in FIG. 11A, first electrical component 2 is bondedonto second electrical component 3, and conductive layer 5 is thenformed. This process can be conducted in the same manner as in the firstembodiment. Refer to FIG. 6A to 6D and the above-mentioned description.It should be noted that second electrical connections 34 and externalconnecting pads 39, both illustrated in FIGS. 6A to 6D, are not providedin the present embodiment. Third passivation layer 8 is not formed atthis stage. Next, as illustrated in FIG. 11B, pillar 10 is formed onconductive layer 5 by plating. First seed layer 51 is not necessarybecause pillar 10 is formed on conductive layer 5. After pillar 10 isformed, third passivation layer 8 is formed on conductive layer 5 andaround pillar 10.

Next, as illustrated in FIG. 11C, an epoxy resin is molded over firstelectrical component 2, second electrical component 3, conductive layer5 and pillar 10. As illustrated in FIG. 11D, the upper portion of themolding material 9 is ground in order to expose the top of pillar 10. Asillustrated in FIG. 11E, terminal 12 for external connection is formedon the top of pillar 10 by plating. As illustrated in FIG. 11F, thewafer is cut halfway from the side of molding material 9. Specifically,molding material 9 is cut along the entire length in the thicknessdirection thereof, and second substrate 35 is cut halfway in thethickness thereof. As illustrated in FIG. 11G, second substrate 35 isground from the opposite surface in order to thin second substrate 35until no uncut portion remains in the thickness direction. Thus, stacks1 are separated. It should be noted that the processes illustrated inFIGS. 11F and 11G may be omitted when stack 101 does not need to bethinned.

Although the present invention has been described by the embodiments,various modifications can be made. For example, as illustrated in FIG.12, second insulating layer 13 may be provided on first side surface 23of first electrical member 2. Conductive layer 5 is insulated from firstelectrical component 2 with first insulating layer 7. However,conductive layer 5 is close to first electrical component 2, inparticular, above first side surface 23 of first electrical component 2(neat first surface 21), and therefore it may be difficult to secureinsulation by simply providing a gap if a defect is generated in firstinsulating layer 7. Second insulating layer 13 enhances the reliabilityof the insulation. Second insulating layer 13 can be provided in thewafer process, and no significant disadvantages occur during thisprocess.

As illustrated in FIG. 13, stack 1 can also be connected to anotherdevice 15, which is indicated by the dashed line, via solder ball 14that is connected to external connecting pad 39.

In the present embodiment, first electrical component 2 has arectangular parallelepiped shape, and first surface 21 and secondsurface 22 are flat and parallel to each other. However, first surface21 and second surface 22 may be curved or uneven. First surface 21 andsecond surface 22 may not be parallel to each other.

Furthermore, in the present embodiment, conductive layer 5 extends fromfirst electrical connection 24 of first electrical component 2 towardthird surface 31 along the side of first side surface 23 of firstelectrical component 2, but conductive layer 5 does not need to beconnected to first electrical connection 24. For example, conductivelayer 5 may extend from an electrical connection of another electricalcomponent, which is mounted on first electrical component 2, on the sideof first side surface 23 of first electrical component 2. In otherwords, the conductive layer may follow any route as long as theconductive layer extends on the side of first side surface 23 of firstelectrical component 2, curves along second portion 42 of adhesive layer4, and extends to third surface 31 of second electrical component 3.

In the present embodiment, first electrical component 2 is a magneticsensor, and second electrical component 3 is an integrated circuit thatis connected to the magnetic sensor. However, a configuration is alsopossible in which first electrical component 2 is an integrated circuitand second electrical component 3 is a magnetic sensor. That is, it ispossible that either first electrical component 2 or second electricalcomponent 3 is a magnetic sensor and the remaining component is anintegrated circuit that is connected to the magnetic sensor.

In the present embodiment, first electrical component 2 is mounted onsecond electrical component 3. However, a third electrical component maybe mounted on second electrical component 3. In this case, the thirdelectrical component may be mounted on the surface of second electricalcomponent 3 on which first electrical component 2 is mounted (thirdsurface 31), but may be mounted on the surface opposite to third surface31, that is, fourth surface 32.

Although certain preferred embodiments of the present invention havebeen shown and described in detail, it should be understood that variouschanges and modifications may be made without departing from the spiritor scope of the appended claims.

LIST OF REFERENCE NUMERALS

-   1 stack-   2 first electrical component-   3 second electrical component-   4 adhesive layer-   5 conductive layers-   6 holding means-   7 first insulating layer-   9 molding material-   11 third insulating layer-   13 second insulating layer-   21 first surface-   22 second surface-   23 first side surface-   24 first electrical connection-   31 third surface-   33 second side surface-   34 second electrical connection-   41 first portion-   42 second portion-   K corner portion

What is claimed is:
 1. A stack of electrical components, comprising: afirst electrical component having a first surface, a second surface thatis opposite to the first surface and a side surface that is locatedbetween the first surface and the second surface; a second electricalcomponent having a third surface on which the first electrical componentis mounted, the third surface facing the second surface and forming acorner portion between the third surface and the side surface; anadhesive layer that bonds the first electrical component to the secondelectrical component, wherein the adhesive layer has a first portionthat is located between the second surface and the third surface and asecond portion that is made of a same material as the first portion andthat fills the corner portion; and a conductive layer that extends on aside of the side surface, curves along the second portion and extends tothe third surface.
 2. A stack of electrical components, comprising: afirst electrical component having a first surface, a second surface thatis opposite to the first surface and a side surface that is locatedbetween the first surface and the second surface; a second electricalcomponent having a third surface on which the first electrical componentis mounted, the third surface facing the second surface and forming acorner portion between the third surface and the side surface; anadhesive layer that bonds the first electrical component to the secondelectrical component, wherein the adhesive layer has a first portionthat is located between the second surface and the third surface and acurved second portion that is made of a same material as the firstportion and that fills the corner portion; and a conductive part thatconnects the first electrical component with the second electricalcomponent.
 3. A stack of electrical components, comprising: a firstelectrical component having a first surface, a second surface that isopposite to the first surface and a side surface that is located betweenthe first surface and the second surface; a second electrical componenthaving a third surface on which the first electrical component ismounted, the third surface facing the second surface and forming acorner portion between the third surface and the side surface; anadhesive layer that bonds the first electrical component to the secondelectrical component, wherein the adhesive layer has a first portionthat is located between the second surface and the third surface and acurved second portion that is made of a same material as the firstportion and that is positioned at the corner portion; and a conductivelayer that extends on a side of the side surface, curves along thesecond portion and extends to the third surface.
 4. A stack ofelectrical components, comprising: a first electrical component having afirst surface, a second surface that is opposite to the first surfaceand a side surface that is located between the first surface and thesecond surface; a second electrical component having a third surface onwhich the first electrical component is mounted, the third surfacefacing the second surface and forming a corner portion between the thirdsurface and the side surface; a filling material that has a firstportion that is located between the second surface and the third surfaceand a curved second portion that is made of a same material as the firstportion and that fills the corner portion; and a conductive layer thatextends on a side of the side surface, curves along the second portionand extends to the third surface.
 5. The stack of electrical componentsaccording to claim 1, wherein the conductive layer extends from thefirst surface to the third surface.
 6. The stack of electricalcomponents according to claim 5, wherein the first electrical componenthas a first electrical connection on the first surface, the secondelectrical component has a second electrical connection on the thirdsurface, and the conductive layer extends along the second portion ofthe adhesive layer and connects the first electrical connection to thesecond electrical connection.
 7. The stack of electrical componentsaccording to claim 1, further comprising a holding surface for theadhesive layer between the second electrical component and the adhesivelayer, wherein wettability of the holding surface is larger than that ofthe third surface.
 8. The stack of electrical components according toclaim 1, wherein the holding surface protrudes from the third surfacetoward the first electrical component.
 9. The stack of electricalcomponents according to claim 7, wherein a circumference of the holdingsurface is formed outside a circumference of the first electricalcomponent along an entire circumference thereof, as viewed in adirection perpendicular to the third surface.
 10. The stack ofelectrical components according to claim 1, further comprising a recessthat holds the adhesive layer, wherein the recess is recessed from thethird surface in a direction away from the first electrical component.11. The stack of electrical components according to claim 10, wherein acircumference of the recess is formed outside a circumference of thefirst electrical component along an entire circumference thereof, asviewed in a direction perpendicular to the third surface.
 12. The stackof electrical components according to claim 1, further comprising aframe member that is provided on the third surface and that holds theadhesive layer.
 13. The stack of electrical components according toclaim 12, wherein a circumference of the frame member is formed outsidea circumference of the first electrical component along an entirecircumference thereof, as viewed in a direction perpendicular to thethird surface.
 14. The stack of electrical components according to claim1, wherein a thickness of the second portion monotonically increasestoward the third surface.
 15. The stack of electrical componentsaccording to claim 1, wherein the second portion has a curved shape thatis concave near the corner portion.
 16. The stack of electricalcomponents according to claim 1, further comprising a first insulatinglayer that is provided both between the conductive layer and the thirdsurface and between the conductive layer and the side surface.
 17. Thestack of electrical components according to claim 1, further comprisinga second insulating layer that is provided on the side surface.
 18. Thestack of electrical components according to claim 1, wherein theadhesive layer is made of silicone resin, further comprising: an epoxyresin layer that covers the second portion of the adhesive layer and theconductive layer, and a third insulating layer is provided between thesecond portion of the adhesive layer and the epoxy resin layer.
 19. Thestack of electrical components according to claim 1, wherein either thefirst electrical component or the second electrical component is amagnetic sensor, and the remaining is an integrated circuit that isconnected to the magnetic sensor.